Save the data off the Simrad unit in .gpx format. You don't need a large SD card - 2gb is plenty and preferred and smaller is ok too.
Install Garmin HomePort for PC (discontinued but still works). Go to HomePort>File>Import>New List - create a list with a name you want.
Click on the new list and go to HomePort>File>Import Into (your list name). Import Simrad data into HomePort -it will show up as a collection. Your Simrad data will be imported and you will be able to see the waypoints on the base map. Move around and you should see it.
On the Garmin unit go to manage card and format a new SD card. Then use manage card to save waypoint data to card. This will create a new Garmin card.
Go back to HomePort with this new SD card. Export the collection (it will be saved with the collection name).
Go back to Garmin unit with this SD card. Manage Data - select the collection then replace from card or merge from card.
This is from memory. I'll clean up the above text later today when I have access to my Garmin and PC with HomePort.
Clip from the Simrad manual....
Backing up your system data
Waypoints, Routes, and Tracks that you create are filed in your system. It is recommended to regularly copy these files and your system settings files as part of your back-up routine. The files can be copied to a card inserted in the card reader.
There are no export file format options for the system settings file. The following output formats are available for exporting Waypoints, Routes, and Tracks files:
- User Data File version 5
This is used to import and export waypoints and routes with a standardized universally unique identifier (UUID), which is very reliable and easy to use. The data includes such information as the time and date when a route was created.
- User Data File version 4
This is best used when transferring data from one system to another, since it contains all the extra bits of information these systems store about items.
- User Data file version 3 (w/depth)
Should be used when transferring user data from one system to a legacy product (Lowrance LMS, LCX)
- User data file version 2 (no depth)
Can be used when transferring user data from one system to a legacy product (Lowrance LMS, LCX)
- GPX (GPS Exchange, no depth)
This is the format most used on the web that shares among most GPS systems in the world. Use this format if you are taking data to a competitor's unit.
• Northstar.dat (no Tracks)
Used to transfer data to a legacy Northstar device.